Taller buildings need more shafts because they'll spend more time in transit so unless the occupants have the patience of saints you need lots shafts to keep wait times down. Eventually most tall buildings setup sky lobbies and express lifts that only service a certain range of floors to keep wait times down during peak hours.

It's really rough in convention center hotels when a huge convention comes to town a lot of the time it's practically impossible to get an elevator down from the middle floors because it's already full from the floors above you.